The present invention relates to internal combustion engines, and more particularly to a structural baffle for such engines.
A typical internal combustion engine includes an engine block, pistons, connecting rods, a crankshaft, bearing caps, and an oil pan. Each piston reciprocates within a cylinder in the engine block. The crankshaft includes a crankpin for each piston offset from the primary axis of the crankshaft. Each piston is connected to one of the crankpins by one of the connecting rods. The crankshaft is rotatably secured to the engine block by a number of bearing caps bolted to the engine block. The oil pan is bolted to the engine block to enclose the engine components and provide a reservoir for engine oil.
In operation, a mixture of air and fuel is sequentially introduced into the combustion chambers over each piston and then ignited. The pressure from the resulting explosion drives the piston downward in the cylinder in turn forcing the connecting rod downward. Because of the axial offset of the crankpins during the ignition phase of their respective cylinders, the downward motion of the connecting rod is translated into rotational movement of the crankshaft. Unfortunately, the initial force of the explosion causes the crankshaft to flex or bend along its axis as the piston and connecting rod attempt to force the crankpin to rotate ahead of the rest of the crankshaft. This flexing motion causes the bearing caps to bend laterally and results in undesired torsional vibrations.
Such torsional vibrations are dampened in primarily four ways. First, the conventional crankshaft can be replaced with a heavier crankshaft offering greater resistance to the flexing motion. Second, the conventional bearing caps can be replaced with heavier bearing caps to provide greater resistance to the flexing motion of the crankshaft. Third, a lower crank case housing, or girdle, can be installed to strengthen the bearing caps against flexing. And fourth, a ladder can be installed to bolster the bearing caps and reduce the magnitude of the torsional vibrations. Such ladders are reinforcing pieces that extend between and structurally interconnect the otherwise independent bearing caps.
Another problem inherent in internal combustion engines stems from the turbulence created by the rotational movement of the crankshaft. Because of the close proximity of the oil reservoir to the crankshaft, the air turbulence created by the spinning crankshaft may result in undesired aeration of the engine oil. Further, undesired aeration of the oil may result from sudden movement of the oil into the throw of the crankshaft caused by hard cornering or sudden acceleration or deceleration. In such instances, the oil is cast into suspension as it collides with the moving crankpins and connecting rods, ultimately resulting in aeration.
There is also a concern that oil returning to the oil pan in the normal oil flow path may flow down and hit the spinning crankshaft, resulting in a loss of energy from the system. While this loss of energy is relatively small, it is a significant concern in high performance engines.
To overcome the problems associated with aeration and oil return, many automobile engines are provided with a windage tray or oil pan baffle. The baffle is typically stamped from sheet metal and mounts within the oil pan to provide a turbulence barrier between the crankshaft and the oil reservoir. The baffle shelters the oil from turbulence and prevents movement of the oil into the throw of the crankshaft.